Category Archives: Digital Setting Circles

Thanks to some help and testing from Pete Eschman, I’ve been able to restore support for Orion telescopes to my ASCOM Driver for Digital Setting Circles. Specifically, Orion Sky Wizard 2 and 3 and Orion Intelliscope platforms should now be working. Please let me know if you have problems using the driver with these platforms.

Orion itself gets no credit for this–they repeatedly ignored my requests for technical support on this issue, despite the fact that the ASCOM driver they published was a slightly-modified version of one of my earlier drivers.

I’ve just updated my Digital Setting Circles ASCOM driver, adding a few additional alignment stars in southern constellations at the request of a southern hemisphere user. I added stars in the constellations Carina, Crux, and Grus. Go to my ASCOM driver page and download the new version (1.0.8.0) there.

And an additional note to you southern hemisphere users: if you’re looking for the star Achernar, it’s actually with the constellation Phoenix in my alignment star constellations. Sorry for the confusion.

I’d been hearing lately about some astronomy software for the iPhone/iPad called SkySafari (made by Southern Stars), but not owning either one of those devices myself, I hadn’t really bothered to look into it at all. That all changed when I came across an ad for SkySafari in Sky and Telescope magazine that showed that an Android version was available. Now I became much more interested to see what the fuss was about, so I dropped $14.99 in the Google Play store for the Plus version so I could try it out on my HTC Incredible phone as well as my rooted Barnes and Noble Nook Color. Mostly, I wanted to see if SkySafari would connect to my digital setting circles box via bluetooth. Initial impressions are very good.

I’ve written a small program called EkBoxTester that you can download to aid in testing your Digital Setting Circles interface board after you’ve constructed it. EkBoxTester requires Microsoft .Net 4.0 to be installed on your computer. EkBoxTester consists of a single executable file (EkBoxTester.exe) that can be run from wherever you want. There is no installer–just download and run it.

The source code for EkBoxTester can be downloaded from here. It was written using Microsoft Visual C# 2010 Express Edition–a free but reasonably complete development environment for writing .Net applications in C#. You can use the source code as an example of how to communicate with an EkBox via the serial port.

The kit is much simpler than the serial version–the pull-up resistors were eliminated, the oscillator replaced by a crystal, and a MAX232 chip is no longer needed. The board and encoders are powered by the USB port, too, so no external power supply is needed. The kit includes all the components, including the programmed PIC chip, but does not include the TTL-232-5V cable. The cable must be purchased separately and is readily available from Mouser and Digikey, for about $20 plus shipping.

This kit should work great if you want to run your digital setting circles straight through the USB port of your laptop. However, if your goal is to use a bluetooth connection between your computer/PDA/smartphone and the board, then the serial version of the kit is the one you want to use. Furthermore, this USB version really isn’t adaptable for use with a smartphone or PDA–the TTL-232 USB cable needs to plug in to a PC in order to work.

One thing that puts people off when they consider building their own digital setting circles is the cost of the two rotary encoders that are needed. Building my DSC circuit is fairly inexpensive (maybe $30 or so), but a pair of high-resolution optical encoders can set you back to the tune of $150 or so. Recently, someone posted information about these capacitive encoders on the Palmastro Yahoo! group. Apparently, they work well in digital setting circles applications, and they appear to be electrically compatible with optical encoders. The spec sheet says they’re accurate to 15 arcmin, which is probably good enough for most users. The best part? You can have a pair for about $50. Digi-Key is supposedly a source of these babies.

I was finally motivated to get my hands on some Bluetooth hardware so I could figure out why my latest ASCOM driver wouldn’t work with Bluetooth. I found mine at U. S. Converters. I needed two–one that would plug into a USB port on my notebook (I bought model BLDONG for $9.99), and one that would plug into the serial connector of my digital setting circles interface (BT232B for $45.00). The BT232B serial Bluetooth adapter also requires a gender changer because it has a female DB9 connector just like my DSC interface, so I bought 10GC-D1 for $7.99, too. I know that AirCable sells this kind of stuff, too, but U. S. Converters seemed a little more economical.

For a surprising number of folks, my Digital Setting Circles project is their first introduction to electronics construction techniques–mainly, the art of soldering. If you’ve never seen it done correctly, soldering can be an intimidating prospect. Someone asked me the other day whether there were any YouTube videos of someone constructing my project (none that I know of). That got me thinking–there must be plenty of “how to solder” videos around. So I checked, and sure enough, YouTube has quite a few of them.